Maple on the Beach
Besides SCUBA diving or snorkeling, we can hardly observe the fascinating marine organisms in the field. However, we can seize the chance to observe some of them during low tide, such as the starfish Archaster typicus.
Most Archaster typicus has five arms. Owing to its maple-like body figure and white ventral side, it was given a very beautiful Chinese name as “Flying White Maple”. Its dorsal side is in yellowish-grey color with black spots, which is a very good camouflage color when these starfish lying on sandy bottoms. The body of starfish is in radial symmetry which composes of five equal parts. Each part has its own set of organs which can operate individually. The mouth of starfish is in the middle of ventral side while the anus is on the dorsal side.
Archaster typicus has a unique mating behavior. During the breeding season, the male seeks out a female and then moves on top of her, with his arms alternating with hers. Release of sperms by males is induced after the female released her eggs, but their reproductive organs do not actually meet. This behavior is believed to increase the chances of external fertilization. Though, you may also encounter starfish stacking on others for resting during the non-breeding seasons.
During low tide, you may find this starfish in shallow water of sandy beach of Hoi Ha Wan Marine Park. Yet, please pay attention to the Marine Parks Visitors Codes and do not disturb any marine lives.
Name in Chinese: 飛白楓海星
Scientific name: Archaster typicus
Site of discovery: intertidal zone, the sandy substratum of Hoi Ha Wan Marine Park
Status: common (Can be seen on shores during low tide)